Currently, many different types of sprinklers have been developed and are specialized for different purposes. One common sprinkler comprises a stationary spray head adapted to mount on an upper end of a fixed or pop-up water supply riser. Such a spray head includes one or more water outlets, or spray nozzles, shaped for distributing irrigation water to surrounding vegetation such as grass, shrubs, crops, and other plants. A prime goal for all irrigations systems is efficient and uniform distribution of water over a particular, desired area.
A common measure of irrigation uniformity and efficiency is a scheduling coefficient (SC), which reflects how much extra watering an entire area must receive for every section to receive sufficient water. More specifically, the portion of the area that will receive the least amount of water is identified. This portion is referred to as a critical area. The average amount of water applied throughout the area is determined, and it is then divided by the amount of water received by the critical area. Under ideal conditions, the amount of water received by any area will equal the average amount received over the entire area, and the ratio between these amounts would equal 1.0. Under typical, less than ideal conditions, the SC ratio would be greater than 1.0. Accordingly, the closer to 1.0 that the calculated SC is, the closer to perfect irrigation uniformity and efficiency achieved by the irrigation system.
Typically, the spray heads mounted to a riser are formed from a deflector cap and base, which together define internal flow paths leading to one or more spray outlets or nozzles. Each nozzle distributes water over a desired area in a spray pattern determined by the size, shape, and geometry of the spray nozzle itself, as well as the inlet supply fluid or water flow rate and pressure. For instance, the spray nozzles may be designed to provide an approximate spray pattern radiating from the sprinkler head in a quarter-circle, half-circle, full-circle, or some other portion of a circle. In this manner, the area receiving the spray pattern is typically a circular wedge radiating from the sprinkler head. Though attempts have been made to adapt nozzles to distribute water over an area such as a rectangular area that is not defined as a circular wedge, such attempts have typically suffered difficulties with efficiency and uniformity of distribution.
There are two basic common approaches to irrigating a rectangular area. The first is to simply use a single spray head that has spray nozzles configured to cover a desired area with a wedge-shaped spray sufficiently large to exceed the rectangular area. However, this approach results in significant overspray onto surrounding areas outside of the rectangular area or under watering areas close-in to the spray head. For example, this approach produces overspray from a side yard such that the sprinkler sprays homes or on a neighbor's property, overspray from a boulevard median such that passing vehicles are sprayed, or overspray from a grass strip between a sidewalks and streets that sprays pedestrians or passing vehicles. In addition, a single spray head typically distributes water unevenly because the spray head is unable to project water to proximal and distal regions for even volume distribution over the area to which water is distributed, particularly under varying supply water pressures.
The second approach for covering a rectangular area is to utilize a plurality of sprinkler heads with each having spray nozzles designed for distributing water to a wedge-shaped area. Accordingly, wedge-shaped or circular areas must overlap to irrigate the rectangular area, resulting in inefficient distribution. Furthermore, this approach only serves to reduce the amount of unwanted overspray.
Accordingly, there is a need for an improved spray head that is capable of uniformly and efficiently irrigating a generally rectangular area with little or no overspray.